PE conductor in outer interstices unique flexibility optimization

The (N)TSCGEWÖU 3×50+3×25/3 12/20kV reeling cable has a base ampacity of approximately 210 amperes when installed in free air with standard ambient conditions of 30°C (86°F) and conductor temperature not exceeding 90°C. However, when this same cable is wound in a 3-layer configuration on a cylindrical motorized reel drum—a typical arrangement for port cranes, ship-to-shore gantries, mining equipment, and mobile cargo handling systems—the effective ampacity is dramatically reduced through application of the DIN VDE 0298-4 thermal derating factor of 0.49. This produces a practical continuous ampacity of approximately 102.9 amperes (calculated as 210 A × 0.49), representing less than half the free-air capacity. The cable features three 50 mm² main phase conductors and three 25 mm² grounding conductors arranged in a compact helical geometry, with an outer diameter of approximately 52–58 mm and total weight of approximately 4,300–4,600 kg/km. The derating factor reflects the fundamental thermal reality that cable layers wound inside the drum cannot radiate heat to the surrounding air, trapping thermal energy and forcing the cable to operate at temperatures significantly above the ambient reference condition.